The present invention relates to methods and apparatus for applying a splicing tape to a roll of sheet material. More particularly, the present invention relates to methods and apparatus for lifting a portion of the outer-most layer of sheet material away from a roll of sheet material to form a lifted portion of the outer-most layer, applying a splicing tape to a wound portion of the roll, and applying pressure to the lifted portion of the outer-most layer to progressively place the lifted portion of the outer-most layer in contact with the remainder of the roll and the splicing tape.
With most high volume printing applications, for example printing of newspapers, the sheet material to be printed on (e.g., paper) is provided to a handling station in a large wound roll. During printing, the sheet material is continuously unwound and fed from the roll, via the handling station, to a printing device. Over time, the sheet material supplied by the roll will be depleted, such that the roll must be replaced with a new roll of appropriate sheet material. As would be expected, manufacturers/publishers wish to minimize, as much a possible, the complications and delays associated with changing from a depleted roll to the new roll. To this end, techniques have been developed by which a leading end (or outermost layer) of the new roll is joined to a trailing portion (or innermost layer) of the depleting roll, effectuating a nearly seamless transition from the depleted roll to the new roll at the handling station.
More particularly, splicing tapes can be employed to prepare a joint between the leading end of the new roll and the trailing portion of the depleting roll. The splicing operation can be performed in a static or dynamic mode. In general terms, the static mode entails stopping rotation of the old roll, applying a tape to one or both of the rolls, and then forming a joint there between. Splices that are formed in a static mode are commonly referred to as zero speed splices. Conversely, the dynamic mode prepares a splice without requiring interruption of the continuous production/printing process. That is to say, both the depleting roll and the new roll continue to rotate as the splice is formed. Splices that are obtained in a dynamic mode of operation are usually referred to as flying splices.
A wide variety of splicing tapes are currently available for forming a flying splice. Regardless of the exact form, the flying splice tape is initially adhered to an outer layer of the new roll, with at least a portion of the splicing tape being exposed for subsequent connection to the trailing portion of the depleting roll. A further constraint is that for flying splice applications, the new roll must be provided to the handling station in wound form, so that when the new roll is subsequently rotated in conjunction with the depleting roll, the new roll will not unexpectedly unwind. Thus, the flying splice tape is applied to the new roll in such a way that an outer-most layer of the new roll is secured or otherwise maintained against a second outer-most layer, ensuring that the new roll remains wound prior to splicing.
The particular form of the flying splicing tape typically dictates the manner in which it is initially applied to a new roll of sheet material. For example, some types of splicing tape include destructible nose tabs, such as that described in WO 95/29115, and are applied in a W or V shape. This format is not conducive to automated application. Conversely, the flying splicing tape can assume a form requiring that the leading edge of the outer-most layer be cut at an angle (relative to an axis of the roll), for example as described in U.S. Pat. No. 4,802,632.
These, and other types of splicing tapes, have proven to be quite viable. However, improvements are continually being pursued. To this end, flying splicing tapes have been developed that are applied in a straight line (relative to an axis of the roll) along an outer surface thereof. Due to the straight line of application, these types of splicing tapes are conducive to automated application. For example, U.S. Pat. No. 5,783,029 describes an automated splicing tape applicator that includes a working carriage that cuts a leading edge of the outermost layer and simultaneously applies spaced adhesive labels and a double sided adhesive splice tape across a width of the roll. As shown in FIG. 3 of U.S. Pat. No. 5,783,029, the spaced adhesive labels are quite large, and are positioned to secure the wound outer surface onto itself. The splicing tape is formed over the adhesive labels. Due to this particular application, there is little concern for precisely cutting/locating the leading edge relative to a remainder of the roll, as the adhesive labels easily compensate for any alignment errors.
A more recently developed splicing tape is described in U.S. patent application Ser. No. 09/770,985, filed Jan. 26, 2001 and entitled xe2x80x9cTape For Flying Splice, Method Of Use, And Method Of Manufacture,xe2x80x9d assigned to the same assignee and the teachings of which are incorporated herein by reference. The so-described splicing tape is generally referred to as being a xe2x80x9cseparable splicing tapexe2x80x9d as it includes inner and outer tape elements releasably secured to one another by a separable intermediate layer. The inner tape element is secured to the roll at the intersection of the outer-most layer and the second outer-most layer (i.e., beneath the leading edge of the outer-most layer). The leading edge of the outer-most layer is adhered to an outer surface of the outer tape element. More particularly, the leading edge is positioned such that the outer-most layer encompasses a portion of the outer tape element (preferably, though not necessarily, along an entire width thereof), with a remainder of the outer tape element being xe2x80x9cexposedxe2x80x9d. Subsequently, the trailing portion of the depleting roll is adhered to this exposed portion of the outer tape element, thereby splicing the two rolls. As the outer-most layer of the new roll is pulled away from, or otherwise forcibly unwound from the roll, the outer tape element releases or xe2x80x9cseparatesxe2x80x9d from the inner tape element so that the new roll can then be fully unwound.
The above-described separable splicing tape represents a distinct advancement in the flying splice tape art. However, certain application difficulties not otherwise found with many other types of splicing tapes render automatic application of the separable splicing tape difficult, especially on a mass production basis. First, unlike most other splicing tapes, the separable splicing tape must be applied between the leading edge of the outer-most layer and a remainder of the roll. Thus, the outer-most layer must be partially unwound, the splicing tape applied, and then the leading edge pressed into contact with the splicing tape. Second, on a related point, the separable splicing tape is preferably quite narrow. Thus, registration of the leading edge, that is otherwise partially unwound, relative to the location at which the splicing tape is to be applied is highly important. By way of example, the separable splicing tape may have a width on the order of 1xc2xd inch (3.81 cm). Because a portion of this width must be available for subsequent engagement with the trailing portion of the depleting roll, there is little room for error when locating the tape along the roll relative to a point at which the leading edge will be located when subsequently reapplied. Additional concerns, such as removal of at least a section of a release liner sometimes provided on top of the outer tape element, precise cutting of the splicing tape relative to a side of the roll, etc., are also raised by separable splicing tapes.
In light of the above constraints, separable splicing tapes are currently applied manually. After loading the roll into a loading station, a leading section of the outer-most layer is allowed to freely extend or unwind from a remainder of the roll. The leading section is pulled away from the roll such that an outer surface of the remaining wound portion is accessible. The separable splicing tape, including an outer release liner, is then placed across the wound portion of the roll at a location that is clearly inside of the unwound leading section. Notably, because the splicing tape is applied by hand, it is oftentimes difficult to achieve a xe2x80x9cstraightxe2x80x9d orientation (parallel to a central axis of the roll). Regardless, a portion of the release liner is then removed. The unwound leading section of the outer-most layer is then re-wound to the roll and adhered to the splicing tape. Assuming the splicing tape has been properly located, a portion (or tail) of the outer-most layer will continue to extend from the roll, beyond the point of interface with the splicing tape. This tail material is folded back at the point of interface with the splicing tape, forming a crease. The tail material is then cut from the roll along the crease. Unfortunately, it is virtually impossible for the new leading edge defined by the cut to be precisely formed and located relative to the exposed area of the splicing tape, possibly leading to problems during a subsequent splicing operation. Further, difficulties may be encountered when attempting to lay the leading section of the outer-most layer against the splicing tape. In fact, due to unavoidable human errors, the cut/leading edge may be so displaced relative to the splicing tape and/or creases formed at the point of interface that the resulting arrangement cannot be used. In this case, a length of the sheet material, including that portion to which the splicing tape is adhered, must be removed and discarded, and the process repeated.
Separable splicing tapes, as well as other splicing tapes applied in either a straight across fashion and/or beneath a leading edge of the outer-most layer, provide many advantages to users. However, existing automated applicators cannot satisfy the many application constraints presented by these splicing tapes when used for flying splices. Further, manual application is less than optimal. Therefore, a need exists for an apparatus and method of consistently and automatically applying a splicing tape, especially a separable splicing tape, to a roll that properly cuts and locates the leading edge of the applied splicing tape in a suitable configuration for a flying splice.
One aspect of the present invention provides a method of applying a splicing tape to a roll of sheet material. This method comprises: lifting a portion of an outer-most layer away from a remainder of the roll to form a lifted portion of the outer-most layer; applying the splicing tape to a wound portion of the roll; and applying pressure to the lifted portion of the outer-most layer to progressively place the lifted portion of the outer-most layer in contact with the remainder of the roll and the splicing tape. In one embodiment of the above method, the lifting step includes lifting the portion of the outer-most layer away from the remainder of the roll with a sheet engagement mechanism, and the step of applying pressure to the lifted portion includes applying pressure to disengage the lifted portion from the sheet engagement mechanism. In one aspect of this embodiment, the sheet engagement mechanism includes a vacuum source for lifting the portion of the outer-most layer away from the remainder of the roll.
In another embodiment of the above method, the applying pressure step includes applying pressure with a paper applicator to the lifted portion of the outer-most layer to progressively place the lifted portion of the outer-most layer in contact the remainder of the roll and the splicing tape. In one aspect of this embodiment, the paper applicator includes a roller, and wherein the applying pressure step includes progressively pressing the roller along the outer-most layer and the splicing tape.
In another embodiment of the above method, the method further comprises cutting the lifted portion of the outer-most layer to form a leading edge of the roll, wherein the applying pressure step includes applying pressure to the lifted portion of the outer-most layer to apply the leading edge of the roll to the splicing tape. In another embodiment of the above method, the splicing tape has a first section and a second section, wherein the outer-most layer covers the first section of the splicing tape and the second section of the splicing tape remains exposed adjacent the outer-most layer. In another embodiment of the above method, the method further comprises holding down a portion of the outer-most layer as the lifted portion of the outer-most layer is lifted away from the remainder of the roll.
Another aspect of the present invention provides an apparatus for applying a splicing tape to a roll of sheet material. This apparatus comprises: a sheet engagement mechanism to lift an outer-most layer of the roll to form a lifted portion of the outer-most layer; a taping device to apply a splicing tape to the roll; and a paper applicator to apply pressure to the lifted portion of the outer-most layer to progressively place the lifted portion of the outer-most layer in contact with the remainder of the roll and the splicing tape. In one embodiment of the above apparatus, paper applicator applies pressure to disengage the lifted portion from the sheet engagement mechanism. In another embodiment of the above apparatus, the paper applicator includes a roller for rolling along the lifted portion of the outer-most layer to disengage the lifted portion of the outer-most layer from the sheet engagement mechanism and to progressively press the roller along the outer-most layer and the splicing tape.
In another embodiment of the above apparatus, the apparatus further comprises a sheet cutter to cut the outer-most layer of the roll across a width thereof. In yet another embodiment of the above apparatus, the sheet engagement mechanism includes a vacuum source for lifting the portion of the outer-most layer away from the remainder of the roll. In another embodiment of the above apparatus, the paper applicator holds down a portion of the outer-most layer as the lifted portion of the outer-most layer is lifted away from the remainder of the roll by the sheet engagement mechanism.
In yet another embodiment of the above apparatus, the splicing tape has a first section and a second section, wherein the outer-most layer covers the first section of the splicing tape and the second section of the splicing tape remains exposed adjacent the outer-most layer. In another embodiment of the above apparatus, the taping device further includes a press down roller for pressing the outer-most layer against an outer surface of splicing tape after the paper applicator applies the lifted portion of the outer-most layer to the splicing tape.
Another aspect of the present invention provides an apparatus for engaging a roll of sheet material. This apparatus comprises: a plurality of sheet engagement mechanisms to engage and lift an outer-most layer of the roll to form a lifted portion of the outer-most layer, wherein each sheet engagement mechanism includes a vacuum source and a roll sensor for sensing a spatial position of the roll relative to the sheet material engagement mechanism, wherein each vacuum source only operates when a selected plurality of the roll sensors sense the roll relative to the sheet engagement mechanism. In one embodiment of the above apparatus, each vacuum source includes a plurality of vacuum cups.